To generate postman reporting using newman , you first need to have newman installed in your system. you can follow my post on step by step newman integration with postman.
Once newman is installed , run the following command to generate the cli report.
$ newman run https://www.getpostman.com/collections/youtcollectionID -r cli,json
Newman also provides a way to generate HTML report , before that you need to have Newman HTML package installed.
$ npm install -g newman-reporter-html
Once it is installed you can run your collection using below cli command
$ newman run https://www.getpostman.com/collections/yourcollectionID -r cli,html
The report generated will look like below :